Quantum tunneling frequencies of methyl groups at low temperature can be measured directly by low-field nuclear magnetic resonance (NMR) using our d&QUID (superconducting quantum interference device) spectrometer. From NMR spectra recorded in magnetic fields below 20 mT, tunneling frequencies between I40 and 250 kHz were measured for a homologous series of carboxylic acids at 4.2 K. For solids ...

General Information. Commercial reagents were purchased from Aldrich or Strem and used as suppplied. Reactions were conducted using standard drybox techniques. Non-aqueous reagents were transferred under argon via syringe. Organic solutions were concentrated under reduced pressure on a Büchi rotary evaporator. Dioxane was distilled from sodium benzophenone ketyl and then degassed using the free...

Pulsed Field Gradient NMR experiments, in their original time domain, have been carried out to separate both water and surfactant self-diffusion coefficients in the micel[ar solution of the system cety[trimethy[ammonium bromide/water. These results have been supported by those obtained by NMR experiments performed with a Fourier Transform spectrometer. The water selfdiffusion coefficients were ...

Algorithmic cooling is a novel technique to generate ensembles of highly polarized spins, which could significantly improve the signal strength in Nuclear Magnetic Resonance (NMR) spectroscopy. It combines reversible (entropy-preserving) manipulations and irreversible controlled interactions with the environment, using simple quantum computing techniques to increase spin polarization far beyond...

H NMR spectra to support data for Table 1 and Figure 1: For synthesis of hydrophobically modified dendrimers, dodecyl chloroformate was adjusted to 5, 10 and 20 mol % of G5OH PAMAM dendrimer hydroxyl groups, and the amount of cholesteryl chloroformate was 0.86, 2, 5, and 20 mol % of dendrimer hydroxyl groups. The corresponding modified dendrimers were designated as D1, D2, D3 and C1, C2, C3, C4...

All reagents were purchased from Sigma-Aldrich or Life Technologies and were used as received. Where described below pet. refers to petroleum ether (40–60 °C). All reactions were monitored by thin-layer chromatography (TLC) on pre-coated SIL G/UV254 silica gel plates (254 m) purchased from VWR. Flash column chromatography was carried out with Kiesegel 60 M, 0.04/0.063 mm (200–400 mesh) silica ...

OBJECTIVE To determine whether characterisation of patients' metabolic profiles, utilising nuclear magnetic resonance (NMR) and mass spectrometry (MS), could predict response to rituximab therapy. 23 patients with active, seropositive rheumatoid arthritis (RA) on concomitant methotrexate were treated with rituximab. Patients were grouped into responders and non-responders according to the Ameri...

He is a model of Fermi liquid, isotropic, its Fermi temperature is attainable and the interaction between atoms can be controlled by changing the pressure on the liquid. In this paper we present accurate cw-NMR measurements of the nuclear magnetic susceptibility of liquid He as a function of temperature and pressure. The emphasis has been placed in reliable thermometry, He pressure measurements...

A Dynamic Nuclear Polarisation (DNP) enhanced solid-state Magic Angle Spinning (MAS) NMR spectrometer which uses a 187 GHz (corresponding to (1)H NMR frequency of 284 MHz) Extended Interaction Klystron (EIK) amplifier as the microwave source is briefly described. Its performance is demonstrated for a biomolecule (bacteriorhodopsin), a pharmaceutical, and surface functionalised silica. The EIK i...